Update git submodules

Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/gambia'
  - Find the ODL owner of the BGP entity in the
    cluster in TC 3

    After new Apex release Opendaylight run in container.
    This fix finds the ODL owner of the BGP entity in the cluster for
    containerised installations.

    JIRA: SDNVPN-238
    JIRA: SDNVPN-234

    Change-Id: Iec1abfe3e0be899ab51fe52057b394a4fa15cc49
    Signed-off-by: dimitris.tsiolakis <dmts@intracom-telecom.com>
    (cherry picked from commit 9d550e5108399bc1f85186956dabc6cbe3a3ec85)